Normative Neuroselective
Current Perception Threshold (CPT) Values

The
standardized computerized automated sNCT/CPT evaluation methodology
removes tester and testing method factors from effecting CPT measures
obtained from different populations at different locations and time periods.
In contrast, these factors represent major confounding variables for sensory
nerve conduction velocity studies1.
Numerous studies from the past 28 years have evaluated CPT measures from
healthy individuals from various populations and the following table
summarizes findings from a representative example of these studies. The most
commonly tested sites are the fingers and the toes.

Healthy Mean CPT Values (SD) , 1 CPT = 10
microAmperes

Face

(Trigeminal n)

Finger

(Median n)

Toe

(Peroneal n)

CPT

Frequency

USA

n=338

Korea

n=400

USA

n=334

Japan

n=1632

Taiwan

n=50

USA

n=310

Taiwan

n=50

5 Hz

10(10)

11(8)

46(27)

61(30)

50(25)

73(34)

74(30)

250 Hz

19(14)

21(12)

81(42)

93(44)

78(30)

125(52)

126(50)

2000 Hz

118(52)

99(28)

226(80)

236(62)

230(70)

322(110)

325(106)

The
above measures were obtained using the double-blind forced
choice testing procedure with a resolution of +/- 20 µAmp,
p<0.006. each body site has a characteristic CPT value.

USA
- Neuval® Database II - Normative Data,
Neurotron, Inc. Baltimore, MD, USA, 2001. This normative
data was obtained primarily from the following institutions:
Johns Hopkins Medical Institution, University of Maryland School
of Pharmacology, Creighton University School of Medicine, New
York Medical College, New York University Medical Center, Palmer
College of Chiropractic and
the University of New Mexico School of Medicine.

This graph depicts
average healthy CPT measures. On the horizontal axis are the
three stimulation frequencies and on the vertical axis are the
CPT measures in mAmperes. Two significant characteristics of
healthy CPTs may be easily observed in this graph. The first, is
the significant increase in sensory thresholds, within each site
tested, as the frequency of the stimulus is changed from 5 Hz to
250 Hz to 2000 Hz. The second, is the consistent relationship
between CPT measures recorded from different body sites but
evoked with the same frequency stimulus. Cephalic measures
represented by the trigeminal testing (the lowest line) have
lower or more sensitive values than the median nerve on the
finger (the middle line) and values from the peroneal nerve on
the toe have the highest values. The CPT data analyses will
detect a ratio abnormality when these healthy characteristic
relationships are absent.